Return Idler Trainer

ABSTRACT

An apparatus and method for an automatically pivoting return side idler trainer for returning a drifting conveyor belt back to a central position during operation. The trainer includes a non-collinear shaft having ends fixed to the conveyor structure while a non-collinear tube is pivotally mounted to the shaft. A tapered roller element is rotatably mounted to the tube on each side of the pivotal mounting. The shaft and tube include an offset angle that is determined by the taper angle of the tapered roller elements such that when the trainer is installed, the profile of the roller elements form a level surface along the trainer, parallel to the belt return side, regardless if the belt has a straight or cupped profile. A second embodiment uses a non-collinear shaft to which the tapered roller elements are rotatably mounted and whereby the shaft itself is pivotally mounted to an external conveyor structure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional application claims the benefit under 35 U.S.C. §119(e) of Application Ser. No. 62/396,528 filed on Sep. 19, 2016entitled RETURN IDLER TRAINER and whose entire disclosure isincorporated by reference herein.

BACKGROUND OF THE INVENTION

The present invention relates generally to conveyor belt systems andmore particularly, to an apparatus and method for training the idlers onthe return side of a conveyor belt to automatically center duringoperation.

Conveyor belts are used in a variety of industries to transportmaterials from one place to another. Generally, materials are depositedat one end of a conveyor and are transported to the other end, wherethey are discharged or otherwise removed from the conveyor belt. FIG. 1depicts a conventional conveyor belt system 1 which comprises an endlessconveyor belt 4 that moves around a tail pulley 2 and a head pulley 3. Aload L, provided at load station LS, is delivered onto the delivery side4A of the pulley 4 just forward of the tail pulley 2. The load L isconveyed on the delivery side 4A in the direction 7A toward the headpulley 3 where off-load station OLS dumps the load L into a receptacle 8(bin, hopper, etc.). The return side 4B of the conveyor belt 4 moves inthe direction 7B back to the tail pulley. To assist the pulleys 2-3,idler roller (“idlers”) are provided underneath each pulley side 4A/4B,namely, delivery side idlers 5 for the delivery side 4A and return sideidlers 6 for the return side 4B. Conveyor belts 4 ideally run centeredwithin the conveyor structure. However, certain conditions cause theconveyor belt 4 to move left or right as it travels. This travel isundesirable as it can cause damage to the conveyor belt 4 edge,structure or components. The delivery side idlers 5 and the return sideidlers 6 can be used to correct for this undesirable travel.

With particular reference to the delivery side idlers 5, to assist incontaining the load material L upon the delivery side 4A of the conveyorbelt 4 during transport, the delivery side 4A of the conveyor belt 4 canbe formed into a “trough” configuration. FIG. 2 provides an end viewlooking down the conveyor belt 4 along line 2-2 of FIG. 1 showing onedelivery side idler 5 which forms the delivery side 4A of the conveyorbelt 4 into a “trough” configuration to assist in containing the loadmaterial L. This is typically accomplished via the use of a centerroller having angled idlers on each side of the center roller (see U.S.Pat. No. 2,225,276 (Parker)) or by having a Y-shaped support havingidlers on each leg of the upper portion of the “Y” (see U.S. Pat. No.6,405,854 (Cumberlege)). See also U.S. Pat. No. 1,705,558 (Cuddihy);U.S. Pat. No. 1,963,099 (Robins); U.S. Pat. No. 2,561,641 (Thomson);U.S. Pat. No. 2,815,851 (Yoshimura) and U.S. Pat. No. 6,173,830(Cumberlege, et al.). In addition, due to the uneven loading of thecontent on the trough-configured conveyor belt, the sides of theconveyor may tend to “creep” along either one of the angled idlers,thereby mis-aligning the conveyor belt. To correct for this “creep”self-aligning tracking assemblies are introduced at predeterminedlocations along the trough-configured conveyor belts 4. See also TrackerRoller Systems Type R/RG/RC/RRC by Hosch-Fordertechnik GmbH, or theTapered Self-Aligning Idler Set 2.6.1 by Hebei Xinshan ConveyorMachinery co. Ltd. of Hebei, China.

As for the return side idlers 6, as also shown in FIG. 2, these tend tobe single or dual rollers for guiding the return side 4B back to thetail pulley 2. As also mentioned earlier, the return side idlers 6 canbe used to correct for the undesirable travel of the conveyor belt 4. Asshown in FIG. 3A, a common practice is to angle the return side idlers6A at their side mounting brackets to force the conveyor belt 4 to movealong the center of the conveyor structure (the black arrowhead in FIG.3A indicates the direction that the idler 6A is directing the belt 4).But this requires continuous adjustment due to the wide range of factorsthat cause the belt 4 to move.

To avoid having to continually adjust the return side idlers 6A, anothersolution is to pivotally mount the return side idlers 6B toautomatically adjust the angle of the return side idlers 6B and steerthe conveyor belt 4 back into central alignment. See FIG. 3B. Thisautomatic adjustment feature of allowing the idler 6B to pivot earnsthese idlers the term of “training idlers” whereby the training idlerhas a central pivot, thereby allowing the idler to pivot in thedirection needed to steer the belt 4 back to center. Furthermore, invariations of these training idlers, vertical rollers 9 (the tops ofwhich are only shown in FIG. 3B) are used to force the idler 6B topivot. In particular, the edge of the return side 4B of the conveyorbelt 4 contacts the roller 9 and moves that end of the idler 6 in thedirection of the conveyor belt 4 movement. This movement of the idler 6Bthereby causes the conveyor belt 4 to begin working its way back to thecenter of the conveyor structure. However, there are several problemswith the vertical guide rollers 9:

-   -   the conveyor belt 4 must move a significant distance for the        edge of the conveyor belt 4 to contact the rollers;    -   vertical guide rollers are large assemblies and require a large        footprint to operate; conventional conveyor systems are designed        around having a standard return side idler, and thus cannot        support a larger footprint (i.e., the vertical guide rollers);        and    -   contact between the conveyor belt 4 edge and the vertical guide        rollers causes damage to the rollers and the conveyor belt edge.

Another style of return side idlers 6C involve the use of tapered idlerends (see U.S. Pat. No. 5,911,304 (Cumberlege)) which solve some of theproblems associated with the vertical guide rollers 9. As shown in FIG.3C, as the return side 4B of the conveyor belt 4 moves from the centerof the idler 6C, the tapered ends 10 of the idler 6C cause the conveyorbelt 4 to contact part of the idler 6C with a smaller diameter. As shownin FIG. 3C, the speed differential caused by the difference in diameter(viz., D2<D1) forces the one side of the idler 6C to drag forward,thereby “training” the conveyor belt 4 back to center. However, problemsexist with these return side idlers 6C, namely:

-   -   as shown in FIG. 3D, some conveyor belts 4 develop a “cupped”        profile that causes the conveyor belt sides to “flare” upward        which does not permit the belt 4 sides to contact the tapered        ends 10 of the idler 6C; the cupped profile typically occurs        from the “trough” configuration on the delivery side 4A of the        conveyor belt 4;    -   in certain high tension applications, the conveyor belt 4        maintains a straight profile (see FIG. 3E) but due to the        smaller diameter of the tapered ends 10, those ends are also        “out of contact” with the return side 4B of the conveyor belt 4.

Thus, in view of the foregoing, there remains a need for a return sideidler that does not suffer from the above-identified problems ofconventional return side idlers and thereby maintains sufficient contactwith return side of the conveyor belt to “train” the belt, regardless ifthe return side is cupped or straight, back to center during operation.

All references cited herein are incorporated herein by reference intheir entireties.

BRIEF SUMMARY OF THE INVENTION

An apparatus for providing automatic adjustment of the return side of aconveyor belt, operating in a conveyor structure, that has drifted fromits central position during operation is disclosed. The apparatuscomprises: pair of tapered roller elements rotatably mounted to anon-collinear pivoting member, wherein each of the pair of taperedroller elements is tapered from one end of the roller element to itsopposite end and wherein the pair of tapered roller elements arerotatably mounted on opposite sides of a pivot point of thenon-collinear pivoting member; and the pair of tapered roller elementsform a profile that is parallel to and in contact with a horizontalportion of the return side of the conveyor belt, and wherein the taperedroller elements rotate and pivot automatically to restore the conveyorbelt to its central position.

A method for providing automatic adjustment of the return side of aconveyor belt, operating in a conveyor structure, that has drifted fromits central position during operation is disclosed. The methodcomprises: providing a pair of tapered roller elements on opposite sidesof an angled member that pivots in a plane parallel to the return sideof the conveyor belt, and wherein each of the tapered roller elements istapered from one end of the roller element to its opposite end;positioning the tapered roller elements into contact with the returnside of the conveyor belt such that the pair of tapered roller elementsform a profile that is parallel with a horizontal portion of the returnside of the conveyor belt; and wherein the angled member automaticallypivots and the tapered roller elements automatically roll against thereturn side of the conveyor belt for restoring the conveyor belt to itscentral position during conveyor belt operation.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

Many aspects of the present disclosure can be better understood withreference to the following drawings. The components in the drawings arenot necessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the present disclosure. Moreover, in thedrawings, like reference numerals designate corresponding partsthroughout the several views.

FIG. 1 is a functional diagram of a prior art conveyor belt system fordelivering a load L from a load source LS to an off-loading station OLSand depicting the use of delivery side idlers and return side idlers;

FIG. 2 is view of a prior art delivery side trough training idler takenalong line 2-2 of FIG. 1;

FIG. 3A are three bottom views of a prior art return side idler, whichis manually adjustable, taken along line 3A-3A of FIG. 2, showing fromleft to right: centered belt operation, slight training by idler andextreme training by idler;

FIG. 3B are three bottom views of another prior art return side idler,which is automatically adjustable and uses vertical side rollers, takenalong line 3B-3B of FIG. 2, showing from left to right: centered beltoperation, slight training by idler and extreme training by idler;

FIG. 3C are three bottom views of another prior art return side idler,which is automatically adjustable and uses tapered ends, taken alongline 3C-3C of FIG. 2, showing from left to right: centered beltoperation, slight training by idler and extreme training by idler;

FIG. 3D is a cross-sectional view of the prior art return side idler ofFIG. 3C, taken along line 3D-3D of FIG. 3C, and where a “cupped” profileof the return side of the conveyor belt is encountered by the returnside idler;

FIG. 3E is a cross-sectional view of the prior art return side idler ofFIG. 3C, taken along line 3E-3E of FIG. 3C, and where a “high-tension,straight” profile of the return side of the conveyor belt is encounteredby the return side idler;

FIG. 4 is an elevation view of the return side training idler of thepresent invention;

FIG. 4A is a top view of the return side training idler of the presentinvention;

FIG. 4B is a cross-sectional view of the return side training idlertaken along line 4B-4B of FIG. 4A;

FIG. 4C is a cross-sectional view of one of the roller elements of thereturn side idler;

FIG. 4D is a side view of the return side idler showing an exemplaryelevation control mechanism;

FIG. 5 shows the return training idler of the present inventionoperating when the conveyor belt is centered;

FIG. 5A shows the return training idler of the present inventionautomatically pivoting to begin returning a slightly “drifting” conveyorbelt back towards center;

FIG. 5B shows the return training idler of the present inventionautomatically returning a highly drifted conveyor belt back to center;

FIG. 6 shows how the return training idler of the present inventionoperates to center the “drifting” conveyor belt even when a “cuppedprofile” of the conveyor belt is encountered;

FIG. 7A is a top view of the non-collinear shaft of the return idlertrainer;

FIG. 7B is a side view of the non-collinear shaft of the return idlertrainer;

FIG. 7C is cross-sectional view of the non-collinear pivot tubeinstalled on the non-collinear shaft;

FIG. 7D is a top view of the non-collinear pivot tube shown in a maximumpivot state, impacting the fixed non-collinear shaft;

FIG. 7E is cross-sectional view of one of the roller elements using an“indirect bearing coupling”, namely, a roller tube to which the bearingsare secured;

FIG. 8A is a cross-sectional view, similar to FIG. 4B, but showing asecond embodiment of the return idler trainer which uses an externalpivot;

FIG. 8B shows the second embodiment of the return idler trainer beingused with the return side of a conveyor belt having a cupped profile;

FIG. 8C is a side view of FIG. 8D showing the stop mechanism for thesecond embodiment of the return idler trainer;

FIG. 8D is a partial view, taken along line 8D-8D of FIG. 8A, showingthe stop mechanism with the idler in its neutral, belt-centeredposition;

FIG. 8E is a partial view, taken along line 8E-8E of FIG. 8A, showingthe stop mechanism with the idler in a maximum pivoted direction,resting against one stop, to “train” the belt back to its centeredposition; and

FIG. 9 is a functional diagram showing a pivoting range motion thatmaximizes the training capability of the second embodiment of the returnidler trainer looking down at the top of the idler trainer, with thepivoting shaft shown partially and in alternative pivoting conditionsand with the conveyor belt shown partially.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the figures, wherein like reference numerals representlike parts throughout the several views, exemplary embodiments of thepresent disclosure will be described in detail. Throughout thisdescription, various components may be identified having specificvalues, these values are provided as exemplary embodiments and shouldnot be limiting of various concepts of the present invention as manycomparable sizes and/or values may be implemented.

To overcome the problems of the prior art return side idlers 6, as shownin FIGS. 4A-4B, the present invention is a return side idler 20comprising two, fully-tapered roller elements 22A/22B that arepivotally-mounted to a fixed non-collinear shaft 24 (FIG. 4B), as willbe discussed below. The relative angle of the shaft 24 matches the angleof the taper of the roller elements 22A/22B. This, in turn, provides thetrainer idler 20 a linear top profile that is parallel to the bottom ofthe return side 4B of the conveyor belt 4. With each roller element22A/22B being completely tapered, no matter the profile of the conveyorbelt 4, the trainer idler 20 is engaged with the belt 4. When theconveyor belt 4 is running centered with the system (FIG. 5), theportion of the return side 4B contacting the idler 20 is contactingequivalent diameters on either roller element 22A and 22B. If theconveyor belt 4 begins to drift towards the right (see arrow 27—seeFIGS. 5A-5B), the left side of the belt 4 moves to a larger diameter onthe roller element 22A while the right side of the belt 4 moves to asmaller diameter on the roller element 22B. As such, the peripheralspeed of the roller element 22B, at the location where the right edge ofthe belt 4 contacts the roller element 22B, will have a peripheral speedwhich is slower than the inner ends 22A′/22B′ (FIGS. 5A and 5B). The endresult of this speed differential is that the belt 4 will tend to dragthe roller element 22B forward, thereby automatically pivoting the idler20 in a counterclockwise motion. This dragging effect tends to steer or“train” the belt 4 in the direction of arrow 26, causing the belt 4 toreturn to its centered position. Once the belt 4 re-centers, the idler20 then rotates clockwise to re-align itself transversely of the belt 4,as shown in FIG. 5. Thus, this pivoting (also referred to as “slewing”)motion occurs automatically to re-steer the belt 4 to its centeredposition. Conversely, should the belt 4 tend to drift to the left, theidler 20 would automatically pivot in a clockwise motion to “train” theconveyor belt 4 back to its centered position, using the same mechanismdescribed above based on the different peripheral speeds and thedragging effect of the roller element. The pivoting or slewing motion ofthe roller elements 22A/22B of the idler 20 occurs in a plane parallelto the return side 4B of the conveyor belt 4 while rolling against thereturn side 4B.

In particular, because the roller elements 22A/22B are tapered alongtheir full lengths, as shown in FIG. 4, the return side 4B of theconveyor belt 4 is always in contact with the roller elements 22A/22B,thereby resulting in the return side idler 20 always engaging the returnside 4B; in other words, because the roller elements 22A/22B taper theirentire length, the speed differential always occurs along the fulllength of the roller elements 22A/22B. Furthermore, even where a “cuppedprofile” of the return side 4B occurs (see FIG. 6) and the edges E1/E2of the return side 4B are not in contact with the roller elements22A/22B, the majority of the taper of the roller elements 22A/22B are incontact with the return side 4B and, as such, those tapered portions can“train” the return side 4B back to center of the conveyor structure.

As shown most clearly in FIG. 4B, the structure of the return side idler20 basically comprises the non-collinear shaft 24, a non-collinear pivottube 28, bearings 30A/30B and the roller elements 22A and 22B. Inparticular, the roller elements 22A/22B are rotatably mounted on thenon-collinear pivot tube 28. In addition, end caps 32A/32B (e.g.,rubber) are provided on each end of the shaft 24 to prevent materialfrom entering the pivot tube 28. Each roller element 22A/22B comprises aroller shell 22C/22D (e.g., steel) that is rotatably movable about thebearings 30A/30B, respectively. Formed on the outside surface of theroller shells 22C/22D are the respective roller laggings 22E/22F thatprovide the tapered surfaces to the roller elements 22A/22B. FIG. 4C iscross-sectional view of one of the roller elements, namely, rollerelement 22B (it being understood that roller element 22A is constructedsimilarly), and depicts the taper angle θ (by way of example only, 2°)which is the angle between the roller shell 22D's outer surface and theoutside surface of the roller lagging 22F (FIG. 4C). The taper angle θis used to determine the offset angle α of the non-collinear shaft 24and the non-collinear pivot tube 28, shown in FIGS. 7A-7B. Inparticular, the angle α is defined by 180°−2θ. As such, when the returnidler trainer 20 is installed in the conveyor system, the top profile ofthe roller elements 22A/22B form a level surface over the full length ofthe return idler trainer 20 that is parallel to and in contact with ahorizontal surface of the return side 4B of the conveyor belt 4, asshown most clearly in FIG. 4B.

As shown most clearly in FIGS. 7A-7B, the shaft 24 (e.g., steel)comprises a center portion 24A having a channel 24B (FIGS. 7A-7B). Thenon-collinear pivot tube 28 (e.g., steel) is slid over the shaft 24 anda pivot pin/bushing 24C (also referred to as an “internal pivot”) ispositioned within the channel 24B. As such, with the ends 23A/23B (FIGS.4 and 7C) of the shaft 24 fixed, using an elevation control mechanism37A/37B (see FIGS. 4A-4B) during operation, the pivot tube 28 is able topivot about the shaft 24 as shown most clearly in FIG. 7D. It should benoted that FIG. 7D also depicts the maximum rotational displacement ofthe pivot tube 28 since the inside surface of the pivot tube 28 hascontacted the shaft 24 at different locations. In addition, the offsetangle α of the shaft 24/pivot tube 28 also provides for a larger gap 36(FIG. 4) on the bottom of the idler 20. As a result, any material thatfalls through the top of the idler 20 will be discarded through the gap36.

The bearings 30A/30B can be fixed on the outside surface of the pivottube 28, as shown in FIG. 4B and the roller shells 22C/22D rotate aboutthose bearings. Alternatively, as shown in FIG. 7E, instead of fixingthe bearings 30A/30B directly to the pivot tube 28, the bearings 30A/30Bcan be fixed to a separate inner roller tube 34 (e.g., steel) which isthen slid over the pivot tube 28, and hence referred to as an “indirect”mount to the pivot tube 28. The alternative locations of the bearings30A/30B, namely, directly or indirectly to the pivot tube 28, arepreferably implemented in a removable manner to make replacing theroller elements 22A/22B easier. In addition, whether the direct orindirect configuration is used, the bearings 30A/30B are completelysealed from the outside via the use of rotary seals as well as via theend caps 32A/32B.

As shown most clearly in FIG. 4D, the elevation control mechanism37A/37B allows the height or elevation of the idler 20 to be adjustablewhile at the same time fixing the ends 23A/23B. The following discussionis for one of the elevation control mechanisms 37A, it being understoodthat it applies to the other elevation control mechanism (ECM) 37B. TheECM 37A comprises an adjustment plate 50 having an aperture 51 therein.A bracket 52 receives the shaft end 23A or 23B within a center hole 53and the end of the shaft 23A/23B is then releasably secured to thebracket 52 using a nut 54. The bracket 53 can then be releasably securedat various elevations via screw/bolts 55 that pass through holes in thebracket 52 and into corresponding holes 56 in the adjustment plate 50.The overall ECM 37A or 37B is secured to the conveyor system (not shown)or other fixed structure via a top member 57.

The roller elements 22A/22B are constructed of abrasive resistant rubberin normal conditions or of high durometer urethane in heavy dutyapplications. The roller elements 22A/22B also comprise grooves todirect water away from the center of the return idler trainer 20 whenthe trainer 20 is exposed to wet applications.

It should be further noted that openings between fixed and pivotingcomponents of the return idler trainer 20 that permit the trainer 20 topivot are capped/covered using a flexible seal which does not impede themovement of the trainer 20. In addition, any gaps that occur from usingtwo independent roller elements 22A/22B are capped in such a way as toprevent build-up from occurring.

The embodiment disclosed in FIGS. 4-7E involve the use of an “internal”pivot. In particular, with the non-collinear shaft 24 ends fixed, thepivot tube 28 pivots internally about the pivot pin/bushing 24C. FIGS.8A-8E depict a second embodiment 120 whereby the return idler trainerpivots about an external pivot. As such, external stops are needed tolimit the pivoting range of the second embodiment 120, as will bediscussed in detail below.

In particular, in the second embodiment 120, a non-collinear shaft 128(e.g., steel) replaces the non-collinear shaft 24/non-collinear pivottube 28 assembly and thus there is a need to limit the pivoting range ofthe idler embodiment 120; this is accomplished by introducing anextension and associated stops on at least one end of the idlerembodiment 120 (most clearly shown in FIGS. 8C-8E); this is by way ofexample only and other pivoting range limitation mechanisms are includedwithin the broadest scope the present invention.

The shaft 128 comprises a central portion 124A having a pivot pin 124Chaving a distal end 127 that is adapted for insertion into a receptacle131 of an idler support base portion 129. Elevation control mechanisms(ECMs) 137A/137B are coupled to the idler support base portion 129 topermit the height or elevation of the idler 120 to be adjusted up ordown. The ECMs 137A/137B comprise adjustment plates 150A/150B thatpermit this height adjustment, along the lines discussed previously withECMs 37A/37B but more simpler in configuration since the ECMs 137A/137Bdo not couple to the ends of the non-collinear shaft 128.

All other aspects of the return idler trainer 120 are identical to thereturn idler trainer 20 discussed previously, including the taper angleθ and offset angle α. Furthermore, although FIGS. 8A-8B show thebearings 30A/30B being secured to the shaft 128, it should be understoodthat the indirect coupling (viz., the bearings 30A/30B being coupled tothe separate inner roller tube 34, as shown in FIG. 7E) is also withinthe broadest scope of the return idler trainer 120. In particular, theseparate inner roller tube 34 would be slid over shaft 128, as discussedpreviously with regard to the pivot tube 28 of the first embodiment 20.

As mentioned previously, the second idler embodiment 120 comprises anexternal stop mechanism 160, as best shown in FIGS. 8C-8E. Inparticular, the external stop mechanism 160 comprises an extension 162coupled (e.g., threadedly engaged, etc.) to one end (e.g., shaft end123A) of the non-collinear shaft 128. The extension 162 is passesthrough an end cap 132A that prevents the entry of debris through theend 123A of the shaft 128; a corresponding end cap 132B is secured tothe opposite end 132B of the shaft 128 (see FIGS. 8A and 8B) for thesame reason. The extension 162 has a free end 162A that can make contactwith a respective stop 164A or 164B, depending on which way the idler120 is pivoting. Each stop 164A/164B can be adjusted via a stop stud166A/166B that is displaceable (e.g., threaded engaged, etc.) withregard to a respective base plate 168A/168B which are secured or formpart of the adjustment plate 150A. As such, FIGS. 8C-8D depict thereturn idler trainer of the second embodiment 120 in its non-training orbelt-centered condition. In contrast, FIG. 8E depicts the extension 162resting against stop 164A which indicates the maximum “training” aspectof the idler 120 when the belt 4 has drifted

In view of the above, with the pivot pin 124C inserted into thereceptacle 131, the return idler trainer 120 is able to automaticallypivot to “train” the conveyor belt 4 to return to the center position,in the same manner as discussed above with regard to the firstembodiment 20. FIG. 8B depicts how the second embodiment 120 also can“train” the conveyor belt 4 to return to the center position even if thereturn side 4B has a “cupped profile” where the belt edges E1 and E2 areout of contact with the roller elements 22A/22B.

It should be further noted that either return training idler embodiments20/120 can be installed on conveyor belts of varying width, e.g., beltwidth +9 or belt width +15 frame spacing. As can be appreciated, withregard to the first embodiment 20, as the length of the shaft 24increases (for use on wider conveyor belts), the amount of pivoting bythe idler 20 decreases due to the impact of the shaft pivot tube 28against the shaft 24 (see FIG. 7D) at a longer distance from theinternal pivot point 24C. As such, the idler 20 tends to be used onsmall conveyor belts. In contrast, with regard to the second embodiment120, without the stop mechanism 160, the shaft 128 could pivot in anunlimited condition. As such, the second embodiment 120 can be used on awide variety of conveyor belt sizes, especially large conveyor belts(e.g., 120 inches wide). Because of the wide range that the shaft 128can pivot, the stop mechanism 160 can be adjusted to provide a desirablerange (β) of pivot motion of the idler 120 that achieves maximum utility(i.e., maximum training capability, i.e., the ability of the pivotingidler 120 to restore the conveyor belt back to its centered position),as referenced from a transverse conveyor belt axis when the idler 120 iscentered. By way of example only, an exemplary optimum rotation angle inthat pivot motion range (β) may comprise 4.5° from a transverse conveyorbelt axis when the idler 120 is centered, as shown in FIG. 9.

While the invention has been described in detail and with reference tospecific examples thereof, it will be apparent to one skilled in the artthat various changes and modifications can be made therein withoutdeparting from the spirit and scope thereof.

What is claimed is:
 1. An apparatus for providing automatic adjustment of the return side of a conveyor belt, operating in a conveyor structure, that has drifted from its central position during operation, said apparatus comprising: a pair of tapered roller elements rotatably mounted to a non-collinear pivoting member, each of said pair of tapered roller elements being tapered from one end of said roller element to its opposite end and wherein said pair of tapered roller elements are rotatably mounted on opposite sides of a pivot point of said non-collinear pivoting member; and said pair of tapered roller elements forming a profile that is parallel to and in contact with a horizontal portion of the return side of the conveyor belt, said tapered roller elements rotating and pivoting automatically to restore the conveyor belt to its central position.
 2. The apparatus of claim 1 wherein each of said tapered roller elements comprises a similar taper angle and wherein said non-collinear pivoting member comprises an offset angle derived from said taper angle, the combination of said taper angle and said offset angle establishing said profile that is parallel to the horizontal portion of the return side of the conveyor belt.
 3. The apparatus of claim 2 wherein said offset angle is defined as twice the taper angle subtracted from 180°.
 4. The apparatus of claim 1 further comprising an elevation adjustment mechanism for permitting said apparatus to be adjusted in height.
 5. The apparatus of claim 2 wherein said non-collinear pivoting member comprises: a non-collinear shaft having two opposing ends that are fixed to the conveyor structure; and a non-collinear hollow tube in which said non-collinear shaft is disposed, said non-collinear tube being pivotally-mounted to said non-collinear shaft at said pivot point, said pair of tapered roller elements being rotatably mounted on said hollow tube.
 6. The apparatus of claim 2 wherein said non-collinear pivoting member comprises a non-collinear shaft having a pivot pin that is located centrally of said shaft at said pivot point and which is received in the conveyor structure that allows said non-collinear shaft to rotate about said pivot pin, said tapered roller elements being rotatably mounted on said non-collinear shaft and on opposite sides of said pivot pin.
 7. The apparatus of claim 6 further comprising a stop mechanism for limiting a pivoting angle of said non-collinear pivoting member.
 8. The apparatus of claim 7 wherein said stop mechanism is adjustable.
 9. The apparatus of claim 8 wherein said stop mechanism is configured for an optimum pivoting motion range that maximizes the training capability of said idler as measured from an axis representing a centered position of said non-collinear shaft.
 10. The apparatus of claim 5 wherein each of said tapered roller elements rotate on bearings secured to an outer surface of said non-collinear hollow tube.
 11. The apparatus of claim 5 wherein each of said tapered roller elements comprises bearings secured to an outer surface of an inner hollow roller tube positioned within each of said tapered roller elements, each of said inner hollow roller tubes being positioned over a respective portion of said non-collinear hollow tube.
 12. The apparatus of claim 6 wherein each of said tapered roller elements rotate on bearings secured to an outer surface of said non-collinear shaft.
 13. The apparatus of claim 6 wherein each of said tapered roller elements comprises bearings secured to an outer surface of an inner hollow roller tube positioned within each of said tapered roller elements, each of said inner hollow roller tubes being positioned over a respective portion of said non-collinear shaft.
 14. The apparatus of claim 1 wherein said tapered roller elements operate to automatically restore the conveyor belt to its central position when the conveyor belt has a cupped profile defined as the sides of the conveyor belt being out-of-contact with said tapered roller elements.
 15. A method for providing automatic adjustment of the return side of a conveyor belt, operating in a conveyor structure, that has drifted from its central position during operation, said method comprising: providing a pair of tapered roller elements on opposite sides of an angled member that pivots in a plane parallel to the return side of the conveyor belt, and wherein each of said tapered roller elements is tapered from one end of said roller element to its opposite end; positioning said tapered roller elements into contact with the return side of the conveyor belt such that said pair of tapered roller elements form a profile that is parallel with a horizontal portion of the return side of the conveyor belt; and said angled member automatically pivoting and said tapered roller elements automatically rolling against the return side of the conveyor belt for restoring the conveyor belt to its central position during conveyor belt operation.
 16. The method of claim 15 wherein each of said tapered roller elements is formed with a similar taper angle and wherein said step of providing a pair of tapered roller elements comprises forming said angled member based on an offset angle derived from said taper angle, the combination of said taper angle and said offset angle establishing said profile that is parallel to the horizontal portion of the return side of the conveyor belt.
 17. The method of claim 16 wherein said offset angle is defined as twice the taper angle subtracted from 180°.
 18. The method of claim 15 further comprising the step of adjusting the height of said apparatus by manipulating an elevation adjustment mechanism.
 19. The method of claim 15 wherein said step of providing a pair of tapered roller elements on an angled member that pivots comprises: providing a shaft having two portions formed at said offset angle; providing a hollow tube having two portions formed at said offset angle; positioning shaft within said hollow tube to form said angled member; pivotally mounting said hollow tube to said shaft such that said hollow tube can pivot with respect to said shaft when opposite ends of said shaft are fixed to the conveyor structure; and rotatably mounting said tapered roller elements to respective ones of said two portions.
 20. The method of claim 15 wherein said step of providing a pair of tapered roller elements on an angled member that pivots comprises: providing a shaft having two portions formed at said offset angle to form said angled member; pivotally mounting said shaft with a pivot pin, where said offset angle is formed, to the conveyor structure such that said shaft can pivot about said pin; and rotatably mounting said tapered roller elements to respective ones of said two portions.
 21. The method of claim 19 further including a step of introducing a stop mechanism for limiting a pivoting angle of said non-collinear pivoting member.
 22. The method of claim 21 wherein said stop mechanism is adjustable.
 23. The method of claim 22 wherein said step of introducing said stop mechanism comprises configuring said stop mechanism that permits a pivoting motion range of said shaft that maximizes the training capability of said idler as measured from an axis representing a centered position of said shaft.
 24. The method of claim 19 wherein said step of providing a hollow tube comprises securing bearings to an outer surface of said hollow tube to allow said tapered roller elements to rotate about said hollow tube.
 25. The method of claim 19 wherein step of rotatably mounting said tapered roller elements to respective ones of said two portions comprises securing bearings to an outer surface of an inner hollow roller tube positioned within each of said tapered roller elements, each of said inner hollow roller tubes being positioned over a respective portion of said hollow tube.
 26. The method of claim 20 wherein said step of providing a shaft comprises securing bearings to an outer surface of said shaft to allow said tapered roller elements to rotate about said shaft.
 27. The method of claim 20 wherein step of rotatably mounting said tapered roller elements to respective ones of said two portions comprises securing bearings to an outer surface of an inner hollow roller tube positioned within each of said tapered roller elements, each of said inner hollow roller tubes being positioned over a respective portion of said shaft.
 28. The method of claim 15 wherein said step of said angled member automatically pivoting and said tapered roller elements automatically rolling against said return side comprises automatically restoring the conveyor belt to its central position when the conveyor belt has a cupped profile defined as the sides of the conveyor belt being out-of-contact with said tapered roller elements. 